The present invention generally relates to inertial sensor devices and, more particularly, to micromachined inertial sensor devices and methods for making the devices.
With the rapid advance of modern electronic technology, various electronic devices, such as navigation systems, cell phones, and electronic games, require sensors that can accurately determine motions of the devices at low cost with small form factor. Conventional techniques have been developed to bump micro-electro-mechanical-systems (MEMS) chips on ASIC wafers or integrate MEMS with ASIC wafers. However, majority of the existing MEMS sensors measure either acceleration or rotation, but not the 6 degrees-of-freedom (three independent accelerations and three independent rotations) of an object. As such, the existing ASIC wafers for detecting the motion of an object in 6 DOF have large form factors to accommodate multiple MEMS sensors and extra circuits or algorithms to handle the data received from the multiple sensors. Furthermore, fabrication of multiple MEMS and packaging/integration of MEMS with ASIC wafers increase the manufacturing cost of the sensor devices. Thus, there is a need for a single MEMS device that can detect the motion of an object in 6 DOF so that the overall form factor and manufacturing cost of a sensor device that contains the MEMS can be significantly reduced.